Random Evil Pocket Dimensions

d12 Gateway Location

1 Stone Monoliths

2 Magic Mirror

3 Pool of Water

4 Cave entrance

5 Mountain Top

6 Temple Chamber

7 Haunted House

8 Black "Bottomless" Pit

9 Staircase in Dungeon

10 Painting or Mural

11 Sewer System

12 Ancient Ruin

d12 Major Terrain

1 Darkness, everything made from shadows

2 Ice, everything ice covered or in glacial caverns

3 Sea, violent storm tossed churning sea with jagged reefs and islands

4 Mountains, hills, cliffs and rough caves surrounded by storm clouds and lightning

5 Burning volcanic mountains and lava filled caverns

6 Slime filled swamp filled with corpses and dead trees

7 Haunted dark evil forest with wicked faced trees 

8 Blasted and burned ruins in earthquake prone plains

9 Horrible tropical fever jungle filled with blood sucking demon bug swarms

10 Eternal dungeon complex crawling with monsters and demons

11 Haunted black prehuman ruins and monoliths, haunted and mostly lifeless

12 Boiling lakes with pools of sulfur, bubbling mud and mineral deposits

d12 Inhabitants

1 Demon hordes fighting eternally for supremacy

2 Demonic nobility battling for supremacy d4+1

3 Demonic noble rules the world from mighty palace

4 Daemons battling each other for supremacy

5 Chaos beings, formless spawn and mutants screaming and fighting idiotically 

6 Demons fighting invasion of devils from hell

7 Nighthags and minions rule petty territories farming larvae and undead

8 Monster hordes with demon patrons battling for supremacy

9 Legions of damned souls fighting eternally for demon patrons

10 A great old one slumbers while a servitor race worships it

11 Evil deities battle for supremacy with armies of demons and damned mortals

12 Evil damned spirits and undead trapped here, hostile to the living

d12 Why would anyone ever come here?

1 Captive souls or loved one need saving

2 Relics hidden here by forces of evil

3 Hero came here long ago but never returned

4 Secret means to stop a evil being hidden here

5 Cult came to free ancient sleeping evil

6 Great force of good imprisoned here

7 Some being has long lost lore required on mortal world

8 Ingredient for spell or ritual or magic item from here

9 A evil being of power has important knowledge

10 Possible to instigate plane war between evil beings

11 Cultists use to keep prisoners or secrets in a base here 

12 Madman came here to free a long slumbering evil force
 

d12 Constructions and Wonders

1 Temple dedicated to forgotten evil in ruins

2 City where evil beings trade damned souls and larvae

3 Monument to evil entity with slaves toiling to complete

4 Fortress of evil, a bastion against rival evils

5 Floating mass of land, fragment from planes creation

6 Palace of evil entity where they dwell in perverted luxury

7 Tomb ruins of former rulers of plane

8 Great dungeon complex deep within earth

9 Huge open cut mine where millions of damned toil

10 Vast area where pits of larvae are tended by evil beings farming them

11 Farm where slaves toil over strange animals and plants for a great evil

12 A great prison for terrible titan, god, old one or demon lord

d12 Intrusions from other realms

1 Elemental node where evil elementals visit

2 Shadows and beings of darkness lurk here

3 Intruders from nightmare realms

4 Dragons spawned by Tiamat guarding treasure hoards

5 Evil beast folk armies rampaging across realm

6 Cult of evil wizards or priests came here long ago to hide from authorities

7 Giants, titans or some other monster race hiding from ancient wars with the gods

8 Wicked spirits come here when not lurking on mortal world

9 Evil elves hidden here since extermination of home land 

10 Reptilian races with dinosaur minions, some with demonic blood taint

11 Adventurers come here from various worlds seeking glorious battles or patrons

12 Humans long ago came here now many part demon or hideous chaos mutants